British police, investigating last Thursday's attempted bombings on London's transport network, say they have arrested another suspect.

Police said Sunday the man is being held under Britain's anti-terrorism laws. Two other men were arrested Friday, but police have released little information.

Earlier Sunday, police performed controlled explosions on a suspicious package found in northwest London. An official statement said a preliminary investigation found the package may be linked to recent bomb attacks.

Meanwhile, London's police chief apologized to the family of the Brazilian man who was shot and killed by police Friday when officers mistook him for a suicide bomber. Sir Ian Blair expressed his "deep regrets" but added that a shoot-to-kill policy remains in effect following the recent bombings.